With a remarkable growth of related technologies, a great variety of mobile electronic devices are increasingly popularized in these days. Particularly, mobile devices today outgrow their respective traditional fields and hence reach a mobile convergence stage.
Representatively, mobile communication devices are equipped with a variety of functions such as a TV watching function (e.g., DMB (Digital Multimedia Broadcasting) or DVB (Digital Video Broadcasting)), a music playback function (e.g., MP3 (MPEC Audio Layer-3)), a digital camera function, and an internet access function in addition to general communication functions such as voice calling and text messaging.
Additionally, recent mobile communication devices are providing a rich choice of features for convenience and entertainment, as they evolve into so called smart-phones, whereby users can install a variety of user functions at their discretion based on an open source OS. Due to vitalization of the open source market, the current smart-phones may not only provide the multi-functional applications for users, but also allow the users to conduct as many functions of PC as possible, along with a development of high-performance smart-phones.
While a variety of services and applications are available for smart-phones, one of the most commonly used services would be messaging service for exchanging messages among users, such as short messaging service (SMS), multimedia messaging service (MMS), instant messenger, and mobile messenger and so on.
As such a messaging service may be more cost-effective than a calling service and allow users to convey their messages or intentions in simpler way than direct phone calls, this messaging service has shown ever-increasing use and grown, these days, into a unified messaging service integrating the independently served messaging service of various sorts and allowing users to take advantage of diverse add-on features such as file transfer, content sharing, and the like.
In addition, the messaging service offers a presence service. The presence service is intended to provide the users concerned with indication about the current connection of a specific user's terminal device, that is, log-on or log-off state. Unfortunately, this conventional presence service is just provided in the form of simple texting.